A trocar is a common tool in a laparoscopic surgery. An inflating needle is penetrated into an umbilical region of a patient during surgery. Meanwhile, the air is injected into the enterocoelia to expand the enterocoelia space, and then the trocar is penetrated into the enterocoelia to form a channel to facilitate the operation of the surgery. It is obvious for the importance of air impermeability in this process. In order to guarantee that the air in the stomach of a patient in the surgery process will not be leaked out, the existing trocar is provided with a sealing structure including sealing plates for sealing when there is a surgical device and a non-return part used when no surgical device is used. The trocar in the prior art has the following defects:
1. Both the sealing plates and the non-return part are provided with an opening. The sizes of the openings are also inconsistent since the functions thereof are different. Generally, in order to better cover the surgical device, the opening of the sealing plate shall be smaller than the opening of the non-return part. However the sealing plates cannot be independently detachable from the non-return part since they are integrated with each other. When a bigger tissue needs to be taken out, although the tissue can be taken out if the sealing structure is removed, air leakage may be caused; and although the tissue can pass through the non-return part if the sealing structure is remained, the tissue will be clamped by the sealing plates, and can be taken out only after being segmented in the enterocoelia, which seriously affects the surgery efficiency and increases the operation difficulty.
2. The opening of the sealing plate is of a type of round hole, which has a higher resistance against insertion and pulling; moreover, the recovery speed is lower after the surgical device is pulled out from the round hole, and air leakage is easily caused when a smaller surgical device is inserted.
3. The external wall of a cannula only has an unilaterally arranged barb, and the device has the risk of bringing the cannula to divorce from a human body when pulling out.
4. The puncturing tool in the prior art is easy to break in use since a visual plastic tool bit is adhered to a stainless toolbar.